EP 0297587 B1 19940907 - Automatic focusing apparatus for automatically matching focus in response to video signal.
Title (en)
Automatic focusing apparatus for automatically matching focus in response to video signal.
Title (de)
Automatische Fokussierungsschaltung für automatische Fokusanpassung in Abhängigkeit von Videosignalen.
Title (fr)
Circuit de localisation automatique pour associer automatiquement la localisation en fonction du signal vidéo.
Publication
Application
Priority
- JP 9731288 A 19880420
- JP 16438287 A 19870630
Abstract (en)
[origin: EP0297587A2] In an automatic focusing apparatus of a video camera, a first focus evaluating value which steeply changes and a second focus evaluating value which gently changes relative to the position of a lens, are detected in response to a video signal obtained in an image sensing circuit (4). A switching circuit (19) alternately selects the first and second focus evaluating values every one field, to apply the same to in-focus state detecting circuits (20, 21), respectively. The in-focus state detecting circuits (20, 21), together with a focusing motor control circuit (10), perform an automatic focusing operation by hill-climbing control. In addition, a calculating circuit (22) calculates the relative ratio of the first focus evaluating value to the second focus evaluating value. The focusing motor control circuit (10) sets the rotational speed of a focusing motor (3) to a normal speed when the calculated relative ratio is smaller than a predetermined value while setting the rotational speed of the focusing motor (3) to a low speed when it is larger than the predetermined value. Therefore, a lens (1) is moved at low speed when the focusing lens is in the vicinity of the in-focus position while being moved at high speed when it is in the defocused state.
IPC 1-7
IPC 8 full level
H04N 5/232 (2006.01)
CPC (source: EP KR US)
H04N 23/60 (2023.01 - KR); H04N 23/673 (2023.01 - EP US)
Designated contracting state (EPC)
DE ES FR GB NL
DOCDB simple family (publication)
EP 0297587 A2 19890104; EP 0297587 A3 19900214; EP 0297587 B1 19940907; AU 1853588 A 19890105; AU 4892090 A 19900517; AU 596018 B2 19900412; AU 609346 B2 19910426; CA 1289236 C 19910917; DE 3851383 D1 19941013; DE 3851383 T2 19950427; ES 2063746 T3 19950116; KR 890001354 A 19890320; KR 930004641 B1 19930602; US 4922346 A 19900501
DOCDB simple family (application)
EP 88110492 A 19880630; AU 1853588 A 19880629; AU 4892090 A 19900130; CA 570629 A 19880628; DE 3851383 T 19880630; ES 88110492 T 19880630; KR 880007896 A 19880629; US 21143488 A 19880624